The association between attention deficit hyperactivity disorder and general anaesthesia - a narrative review

Early childhood general anesthesia and risk of Attention Deficit Hyperactivity Disorder

BACKGROUND

The relationship between early childhood exposure to general anesthesia (GA) and the risk of developing Attention Deficit Hyperactivity Disorder (ADHD) is still uncertain and previous studies have presented conflicting results. This population-based cohort study aimed to investigate the potential relationship between GA exposure and ADHD risk using propensity score matching (PSM) in a large sample size.

METHODS

The study included 15,072 children aged 0-3 years who received GA and were hospitalized for more than 1 day in Taiwan from 2004 to 2014. The nonexposed group was randomly selected through 1:1 PSM from the Taiwan Maternal and Child Health Database (TMCHD). The primary objectives of this study were to determine the incidence rates (IR) and incidence rate ratios (IRR) of ADHD in the two cohorts, employing Poisson regression models.

RESULTS

The GA group and non-GA group each comprised 7,536 patients. The IR of ADHD was higher in the GA group (122.45 per 10,000 person-years) than in the non-GA group (64.15 per 10,000 person-years), and the IRR of ADHD in the GA group was 1.39 (95% CI: 1.26, 1.55). The study found that the number of times of exposure to GA, duration of exposure, male gender, and central nervous system surgery were significant risk factors for ADHD in the future.

CONCLUSIONS

This study's findings suggest that there is a significant correlation between early childhood exposure to GA and the risk of developing ADHD, and GA may be an important risk factor for ADHD in children undergoing surgery. The study also identified several risk factors for ADHD, including the number of times of exposure to GA, duration of exposure, male gender, and central nervous system surgery.

Risk of attention deficit hyperactivity disorder diagnosis following multiple exposures to general anesthesia in the paediatric population: A systematic review and meta-analysis

Objectives

The risk of attention deficit hyperactivity disorder (ADHD) following multiple exposures to anesthesia has been debated. Our objective was to systematically review the literature to examine the association between multiple exposures to general anesthesia before age 5 and subsequent diagnosis of ADHD.

Methods

A systematic search of EMBASE, PubMed, and SCOPUS was performed using key search terms in February 2022. We included studies that: were published after 1980, included only otherwise healthy children who experienced two or more exposures to general anesthetic before age 5, diagnosed ADHD by a medical professional before age 19 years after exposure to general anesthetic, were cross-sectional, case-control, or cohort study, and were published in English. The results (expressed as hazard ratios [HR] and associated 95% confidence intervals [CI]) were pooled using meta-analytic techniques. Studies which did not present their results as HR and 95% CI were analyzed separately. GRADE was used to determine the certainty of the findings. PRISMA guidelines were followed at each stage of the review.

Results

Eight studies (196,749 children) were included. Five reported HR and 95% CI and were subsequently pooled for meta-analysis. Multiple exposures to anesthesia were associated with diagnosis of ADHD before the 19th year of life (HR: 1.71; 95% CI: 1.59, 1.84). Two of the three studies not used in the meta-analysis also found an increased risk of ADHD diagnosis following multiple anesthetic exposures.

Conclusions

There was an association between multiple early exposures to general anesthesia and later diagnosis of ADHD.

Molecular Characterisation of the Mechanism of Action of Stimulant Drugs Lisdexamfetamine and Methylphenidate on ADHD Neurobiology: A Review

Attention-deficit/hyperactivity disorder (ADHD) is a common childhood-onset neurodevelopmental disorder characterised by persistent inattention, hyperactivity and impulsivity. Moreover, ADHD is commonly associated with other comorbid diseases (depression, anxiety, bipolar disorder, etc.). The ADHD symptomatology interferes with subject function and development. The treatment of ADHD requires a multidisciplinary approach based on a combination of non-pharmacological and pharmacological treatments with the aim of ameliorating the symptomatology; among first-line pharmacological treatments are stimulants [such as methylphenidate (MPH) and lisdexamfetamine dimesylate (LDX)]. In this review we explored recent ADHD- and stimulants-related literature, with the aim of compiling available descriptions of molecular pathways altered in ADHD, and molecular mechanisms of current first-line stimulants MPH and LDX. While conducting the narrative review, we applied structured search strategies covering PubMed/MEDLINE database and performed handsearching of reference lists on the results of those searches. The aetiology and pathophysiology of ADHD are incompletely understood; both genetic and environmental factors have been associated with the disorder and its grade of burden, and also the relationship between the molecular mechanisms of pharmacological treatments and their clinical implications. The lack of comprehensive understanding of the underlying molecular pathology makes both the diagnosis and treatment difficult. Few published studies evaluating molecular data on the mechanism of action (MoA) of MPH and LDX on ADHD are available and most of them are based on animal models. Further studies are necessary to improve the knowledge of ADHD pathophysiology and how the MoAs of MPH and LDX differentially modulate ADHD pathophysiology and control ADHD symptomatology.

Mitochondria-Related Ferroptosis Drives Cognitive Deficits in Neonatal Mice Following Sevoflurane Administration

Multiple sevoflurane exposure may result in cognitive deficits in neonatal animals. This study attempted to investigate the potential mechanism of sevoflurane-induced neurotoxicity in developing hippocampus. Neonatal animals received sevoflurane anesthesia, then the behavioral tests and Golgi-Cox staining were employed to detect the effect of sevoflurane inhalation in adult mice. And the mitochondrial function was evaluated using MitoSOX staining, Fluo calcium indicators, mitochondrial permeability transition pore (mPTP) assay, and JC-1 probe after sevoflurane administration. Meanwhile, mitochondrial lipid hydroperoxide and ferroptosis were measured by MitoPeDPP and Mito-FerroGreen signals following sevoflurane exposure. Moreover, the ferroptosis and behavioral performance were assessed after deferiprone (DFP) treatment. The results showed that sevoflurane administration induced cognitive impairment accompanied by reducing dendritic length, density, and nodes. Additionally, sevoflurane exposure elevated mitochondrial ROS production and cytoplasm calcium levels, triggered the opening of mPTP, and decreased the mitochondrial membrane potential (MMP). However, supplement of elamipretide (SS-31) effectively reversed mitochondrial dysfunction. Mitochondrial lipid hydroperoxide production was increased after sevoflurane administration, whereas Fer-1 treatment reduced lipid hydroperoxide formation. Sevoflurane exposure induced mitochondrial iron overload, whereas Mito-Tempo treatment reduced iron accumulation. Prussian blue staining showed that the hippocampal iron deposition was apparently increased after sevoflurane inhalation. Additionally, the ferroptosis-related protein expression (including ACSL4, COX2, GPX4, and FTH1) was significantly changed, whereas DFP effectively suppressed ferroptosis and enhanced sevoflurane-induced behavioral malfunction. These findings demonstrated that sevoflurane administration elicited mitochondrial dysfunction and iron dyshomeostasis and eventually resulted in cognitive impairments, whereas protecting mitochondrial function and chelating neurotoxic iron effectively reversed these pathological processes.

Sevoflurane Exposure in the Developing Brain Induces Hyperactivity, Anxiety-Free, and Enhancement of Memory Consolidation in Mice

Background

Sevoflurane exposure at brain developmental stages has been reported to induce neurotoxicity and, subsequently, results in learning deficits at the juvenile age. In this study, we aimed to investigate the effects of prior early-age sevoflurane exposure on locomotor activity, anxiety, CA1-dependent learning, and spatial memory, as well as synapse changes in mice.

Methods

Totally, 3% sevoflurane was given to neonatal mice at postnatal day 7 for 4 h. These sevoflurane-treated mice were later subjected to open field and Morris water maze tests at their adult age (postnatal days 60–90) to assess their motor activity and spatial learning ability, respectively. The brain slices of sevoflurane-treated and control mice were examined for dendritic spine density and long-term potentiation (LTP) features following behavior tests (postnatal day 60). Protein levels of N-methyl-D-aspartate (NMDA) receptor subtypes and PSD95 in brain lysate were measured by using immunoblotting at the same age (postnatal day 60).

Results

Prior early-age sevoflurane exposure increased the overall moving distance, prolonged the central-area lingering time, and increased the central-area entries of adult mice. Sevoflurane-treated mice spent more time in the target quadrant during the probe test. An increase of the spine density of pyramidal neurons in the CA1 region was observed in sevoflurane-treated mice. NMDA receptor GluN2A subunit, but not the GluN2B or PSD95, was increased in the brain lysate of sevoflurane-treated mice compared with that of control mice. LTP in the hippocampus did not significantly differ between sevoflurane-treated and control mice.

Conclusion

Exposure to sevoflurane for mice during an early brain developmental stage (P7) induces later-on hyperactivity, anxiety-free, and enhancement of memory retention. These observations shed light on future investigations on the underlying mechanisms of sevoflurane’s effect on neuronal development.

A National Population Cohort Study Showed That Exposure to General Anesthesia in Early Childhood Is Associated with an Increase in the Risk of Developmental Delay

This study investigated the relationship between exposure to general anesthesia (GA) and the risk of cognitive and mental disorders. This study has thus investigated the relationships between exposure to GA before the age of 3 and subsequent cognitive and mental disorders in a national-wide research sample. We obtained our subjects from the National Health Insurance Research Database (NHIRD) of Taiwan, which was based on the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). Children in the hospital aged less than 3 years old were included if there was GA exposure or not during the period of year 1997 to 2008. Cox proportional hazard regression models adjusted for potential confounding factors were used to estimate the relative magnitude of the risk associated with GA exposure. The cohort contained 2261 subjects with GA and 4522 children without GA as a comparison group. GA exposure group had a higher rate of developmental delay than in the without GA group (hazard ratio 1.46, p < 0.0001). There was no significant difference in the overall incidence of ADHD, autism and intellectual disability between the GA-exposed group and the comparison cohort. In conclusion, this study reported that children exposed to GA early before the age of three had a small association with increased risk of development delay thereafter.

Association Between Behavioral and Learning Outcomes and Single Exposures to Procedures Requiring General Anesthesia Before Age 3: Secondary Analysis of Data From Olmsted County, MN

BACKGROUND

Two prior population-based (children born in Olmsted County, MN), retrospective cohort studies both found that multiple exposures to anesthesia before age 3 were associated with a significant increase in the frequency of attention-deficit hyperactivity disorder (ADHD) and learning disabilities (LD) later in life. The primary purpose of this secondary analysis of these data was to test the hypothesis that a single exposure to anesthesia before age 3 was associated with an increased risk of ADHD. We also examined the association of single exposures with LD and the need for individualized educational plans as secondary outcomes.

METHODS

This analysis includes 5339 children who were unexposed to general anesthesia before age 3 (4876 born from 1976 to 1982 and 463 born from 1996 to 2000), and 1054 children who had a single exposure to anesthesia before age 3 (481 born from 1976 to 1982 and 573 born from 1996 to 2000). The primary outcome of interest was ADHD. Secondary outcomes included LD (reading, mathematics, and written language) and the need for individualized educational programs (speech/language and emotion/behavior). To compare the incidence of each outcome between those who were unexposed and singly exposed to anesthesia before the age of 3 years, an inverse probability of treatment weighted proportional hazards model was used.

RESULTS

For children not exposed to anesthesia, the estimated cumulative frequency (95% confidence interval [CI]) of ADHD at age 18 was 7.3% (95% CI, 6.5-8.1) and 13.0% (95% CI, 10.1-16.8) for the 1976-1982 and 1996-2000 cohorts, respectively. For children exposed to a single anesthetic before age 3, the cumulative frequency of ADHD was 8.1% (95% CI, 5.3-12.4) and 17.6% (95% CI, 14.0-21.9) for the 1976-1982 and 1996-2000 cohorts, respectively. In weighted analyses, single exposures were not significantly associated with an increased frequency of ADHD (hazard ratio [HR], 1.21; 95% CI, 0.91-1.60; P = .184). Single exposures were also not associated with an increased frequency of any LD (HR, 0.98; 95% CI, 0.78-1.23), or the need for individualized education plans.

CONCLUSIONS

This analysis did not find evidence that single exposures to procedures requiring general anesthesia, before age 3, are associated with an increased risk of developing ADHD, LD, or the need for individualized educational plans in later life.

ADHD symptomatology of children with congenital heart disease 10 years after cardiac surgery: the role of age at operation

BACKGROUND

The aim of the present study was to investigate the differences in ADHD symptomatology between healthy controls and children who underwent cardiac surgery at different ages.

METHODS

Altogether, 133 children (54 patients with congenital heart disease undergoing first cardiac surgery under 3 years of age, 26 operated at the age of 3 or later, and 53 healthy controls) were examined. Patients completed the Youth Self Report (YSR), while their parents completed the Child Behaviour Checklist (CBCL) and the ADHD Rating Scale-IV.

RESULTS

Children receiving surgery for the first time under the age of 3 years were more likely diagnosed with cyanotic type malformation and have undergone to a greater number of operations. However, ADHD symptoms of those treated surgically at or above 3 years of age were more severe than that of the control group or those who were treated surgically at a younger age. The control group and those treated surgically below the age of three did not differ across any of the ADHD symptom severity indicators.

CONCLUSIONS

The age at the time of cardiac surgery might be associated with later ADHD symptom severity - with lower age at operation associated with better outcomes. Further, adequately powered studies are needed to confirm these exploratory findings and investigate the moderators of this relationship.

lncRNA Xist regulates sevoflurane-induced social and emotional impairment by modulating miR-98-5p/EDEM1 signaling axis in neonatal mice

Long non-coding RNA (lncRNA) X-inactive specific transcript (Xist) is involved in apoptosis and inflammatory injury. This study aimed to assess the role of lncRNA Xist in sevoflurane-induced social and emotional impairment and neuronal apoptosis in neonatal mice and hippocampal neuronal cells. The performance in social and emotional tests and the expression levels of lncRNA Xist and microRNA (miR)-98-5p after sevoflurane exposure were measured. Moreover, the effects of suppression of lncRNA Xist on neuronal apoptosis and endoplasmic reticulum (ER) stress were determined. Subsequently, the association among lncRNA Xist, miR-98-5p, and ER degradation-enhancing α-mannosidase-like 1 protein (EDEM1) was explored. Our results showed that lncRNA Xist increased, miR-98-5p decreased, and social and emotional impairment appeared after sevoflurane exposure. Furthermore, suppression of lncRNA Xist improved sevoflurane-induced social and emotional impairment and reduced sevoflurane-induced neuronal apoptosis and ER stress in vivo and in vitro. Moreover, lncRNA Xist negatively regulated miR-98-5p expression, and it contributed to sevoflurane-induced neuronal apoptosis and ER stress by sponging miR-98-5p. Additionally, EDEM1 was identified as a target of miR-98-5p. Our findings revealed that the knockdown of lncRNA Xist ameliorates sevoflurane-induced social and emotional impairment through inhibiting neuronal apoptosis and ER stress by targeting the miR-98-5p/EDEM1 axis.

Neonatal sevoflurane exposure induces impulsive behavioral deficit through disrupting excitatory neurons in the medial prefrontal cortex in mice

Sevoflurane, in particular multiple exposures, has been reported to cause the abnormal neurological development including attention-deficit/hyperactivity disorder (ADHD). This study is to investigate ADHD-like impulsivity in adult mice after repeated sevoflurane exposures at the neonatal stage. Six-day-old pups were exposed to 60% oxygen in the presence or absence of 3% sevoflurane for 2 h and the treatment was administrated once daily for three consecutive days. To assess the impulsivity, the cliff avoidance reaction (CAR) was carried out at the 8th week. Our results showed that repeated sevoflurane treatment increased the number of jumps and shortened the jumping latency in the CAR test. The cortices were harvested for immunostaining to detect c-Fos and calmodulin-dependent protein kinase IIα (CaMKIIα) expression in the medial prefrontal cortex (mPFC). We found that mPFC neurons, especially excitatory neurons, were highly activated and related to impulsive behavior. The activation viruses (AAV-CaMKIIα-hM3Dq) were injected to evaluate the effects of specific activation of mPFC excitatory neurons on impulsive behavior in the presence of clozapine-N-oxide (CNO). Likewise, the inhibitory viruses (AAV-CaMKIIα-hM4Di) were injected in the sevoflurane group to explore whether the mPFC excitatory neuronal inhibition reduced the impulsivity. Our results revealed that chemogenetic activation of mPFC excitatory neurons induced impulsive behavior whereas inhibition of mPFC excitatory neurons partially rescued the deficit. These results indicate that repeated sevoflurane exposures at the critical time induce impulsive behavior accompanied with overactivation of mPFC excitatory neurons in adult stages. This work may further extend to understand the ADHD-like impulsive behavior of the anesthetic neurotoxicity.

Tetramethylpyrazine Attenuated Sevoflurane-Induced Neurotoxicity by Enhancing Autophagy through GPR50/CREB Pathway in SH-SY5Y Cells

Tetramethylpyrazine has shown neuroprotective and axonal outgrowth-promoting effects and can improve cognitive deficit in a rat model of chronic hypoperfusion. However, the role of tetramethylpyrazine in sevoflurane-induced neurotoxicity is still vague. Therefore, this study was designed to investigate the effects and mechanisms of tetramethylpyrazine on sevoflurane-induced autophagy, apoptosis, and the expression of BACE1 and A[Formula: see text] in SH-SY5Y cells. We measured the expression levels of the apoptosis protein markers Bax and Bcl-2, autophagy protein markers Atg5 and LC3-II, BACE1, and A[Formula: see text] in SH-SY5Y cells after sevoflurane treatment and determined the effects of tetramethylpyrazine on sevoflurane-induced expression of these proteins after silencing GPR50 or Atg5 with siRNA in vitro. We found that exposure to 3.4% sevoflurane for 6 h decreased the expression of autophagy protein markers and increased the expression of the apoptosis protein markers, BACE1, and A[Formula: see text] in SH-SY5Y cells. The number of red puncta (autolysosomes) and yellow puncta (autophagosomes) in each SH-SY5Y cell decreased after transient transfection with the mRFP-GFP-LC3 expression plasmid. Silencing of GPR50 decreased the expression of pCREB, Atg5, and LC3-II, while silencing of Atg5 increased the expression of BACE1 and A[Formula: see text] in SH-SY5Y cells. Our results demonstrate that tetramethylpyrazine attenuated sevoflurane-induced neurotoxicity by enhancing autophagy through the GPR50/CREB pathway in SH-SY5Y cells.

MicroRNA-325-3p prevents sevoflurane-induced learning and memory impairment by inhibiting Nupr1 and C/EBPβ/IGFBP5 signaling in rats

Endoplasmic reticulum stress-induced neuronal apoptosis contributes to neurotoxicity observed after sevoflurane exposure. However, the molecular mechanism underlying the resulting learning and memory impairments remains unknown. Here, we investigated the roles of miR-325-3p and Nupr1 in sevoflurane-induced learning and memory impairments in neonatal rats and HCN-2 human cortical neuronal cells. We found that in both neonatal rats and HCN-2 cells, sevoflurane exposure impairs learning and memory in neonatal rats and increases expression of Nupr1, the endoplasmic reticulum stress marker proteins C/EBPβ and IGFBP5, and the apoptosis-related protein markers cleaved-Caspase-3 and Bax. Using bioinformatics tools to identify microRNAs that bind to Nupr1, we found that miR-325-3p is downregulated in hippocampal neurons exposed to sevoflurane. Moreover, Nupr1 knockdown and miR-325-3p overexpression improved the rats’ performance in learning and memory tests and reduced sevoflurane-induced apoptosis in vitro and in vivo. These results suggest that miR-325-3p blocks sevoflurane-induced learning and memory impairments by inhibiting Nupr1 and the downstream C/EBPβ/IGFBP5 signaling axis in neonatal rats. MiR-325-3p may therefore be a useful therapeutic target in sevoflurane-induced neurotoxicity.